1. Field of the Invention
The present disclosure generally relates to a resistive random access memory and, more particularly, to a resistive random access memory having an oxygen-containing resistance changing layer enclosed by materials that do not contain oxygen.
2. Description of the Related Art
Memories have been widely used in various electronic products. Due to the increasing need of data storage, the demands of the capacities and performances of the memories become higher and higher. Among various memory elements, resistive random access memories (RRAMs) have an extremely low operating voltage, an extremely high read/write speed, and high miniaturization of the element size and, thus, may replace the conventional flash memories and dynamic random access memories (DRAMs) as the main stream of memory elements of the next generation.
A conventional resistive random access memory generally includes a bottom electrode, a dielectric layer, a resistance changing layer and an upper electrode. The dielectric layer is arranged on the bottom electrode. The dielectric layer forms a first via-hole. The surface of the bottom electrode is partially exposed to the first via-hole. As such, the resistance changing layer extends from the surface of the bottom electrode, which is exposed to the first via-hole, to an upper surface of the dielectric layer. The upper electrode is arranged on the resistance changing layer. In the above arrangement, an electric field can be applied to switch the resistance changing layer between a low resistance state (LRS) and a high resistance state (HRS). Such a resistive random access memory can be seen in the academic paper entitled “Characteristics and Mechanisms of Silicon-Oxide-Based Resistance Random Access Memory” as published on IEEE ELECTRON DEVICE LETTERS, VOL. 34, NO. 3 on March 2013.
However, after the conventional resistive random access memory operates in a certain number of times, the oxygen ions in the resistance changing layer will gradually disperse. As a result, the resistances of LRS and HRS will gradually become close to each other. For example, after the resistive random access memory is operated for a certain number of times (such as 1*108 times), the resistive random access memory will become inoperable due to the small difference between the resistances of LRS and HRS. Thus, the durability of the conventional resistive random access memory is low.
In light of this, it is necessary to improve the conventional resistive random access memory.